Here's How Long Opened Buttermilk Will Last

Buttermilk is a creamy, tangy liquid that can be added to baked goods, pasta dishes, and even features in Ina Garten's potato salad. The drink gets its tang thanks to bacteria that produce lactic acid, which is added to the milk — basically, it's fermented. But, unless you're a baker or a really good meal planner who regularly turns buttermilk into homemade sour cream, you probably don't use up an opened bottle within a few days. Instead, you're likely left wondering how long you've got before it goes bad.

Buttermilk, once opened, can actually last for up to two weeks, provided it's stored in the fridge and isn't left out on the counter for longer than two hours at a time. Like all milk, it should not be kept in the fridge door, convenient though this might be. However, due to the temperature fluctuations that occur every time you open the fridge, it's best to find a place for it on a low shelf near the back, where it's coolest.

Although buttermilk is cultured, it's important not to introduce new bacteria to the mix. Try not to touch the mouth or rim of the container with any dirty utensils — something that can easily happen when you're cooking or baking with it. You should also avoid drinking directly from the carton. Even if you are the only person in the house who likes buttermilk, germs from your mouth can taint the milk and speed up the spoilage process.

You can also freeze buttermilk if you're not going to use it within the two-week timeframe. Just leave it in the bottle you bought it in provided this container has an airtight lid. If you get your buttermilk in a cardboard carton, you should decant it into a freezer-safe bottle or jar before freezing. Buttermilk can be kept in the freezer for up to three months.

Even though it lasts for up to two weeks in the fridge, buttermilk might start to show signs of spoilage earlier than this. The first indicator that buttermilk is going bad is the smell. While it's true that buttermilk does have a naturally tangy scent, it should nonetheless have a light freshness about it. If you open your container and it smells unnaturally sour or off-putting, it's likely starting to turn and should be poured away.

If you notice a change in texture, from smooth and creamy to thick and chunky, this does not bode well for your buttermilk, nor is it a good sign if the liquid starts to change color. Finally, the easiest way to tell if your buttermilk is bad is the appearance of mold, either on its surface or on the insides of the container. Once you start to get toward the end of the two-week timeframe, peek inside the carton before using the milk, just to make sure that it's still safe and there's nothing furry starting to grow.